’73 Newport w/3,500 miles- What’s it worth?

Hi everyone-

I just came across a 1973 Newport sedan, black top over metallic brown body, with 3,500 miles. I did a pretty thorough inspection of the car and, while it does not have any documentation to prove it, it seems to be the real deal. It is as about a plain jane Newport as you could find. The only option I could identify was a vinyl top. It is near- immaculate and the underside is clean. Current owner replaced the battery and fuel tank. It does have an obvious carb problem. Given what I saw I'd say the floats are sunk. Very light surface rust on the underside of the passenger side rear quarter, otherwise none found. Engine compartment and trunk dusty, but appear to be a snapshot from 1973. 400 ci engine. The car runs and drives but is running rough and super rich. Seller is looking for $8,000, I offered what I thought was a generous $4,300. What do you guys think this car is worth?
Author: jtpoltrock